Carboxyazetidine is of interest for selectively sterilizing the male parts of plants: European patent application 29265. It can be prepared from 1-benzhydrylazetidine-3-ol, which is prepared by the reaction of epichlorohydrin with benzhydrylamine: A. G. Anderson, Jr. and R. Lok, Journal of Organic Chemistry, 1972, volume 37, pages 3953-5. However, the introduction of a benzhydryl group is very inconvenient for an economically practicable synthesis route, since the size of that group greatly increases the bulk of material to be processed, only to be removed once its protective function is no longer required. It would be economically very desirable to use a protective group less bulky than the benzhydryl group, for example, the benzyl group, but previous attempts to react epichlorohydrin with benzylamine have failed to produce any significant yield of the desired cyclized azetidine product.
Applicant's coworker found that the use of an aqueous reaction medium enables useful yields of 1-substituted azetidines to be obtained from an epoxy halide and less bulky amines such as benzylamine, which process forms the subject of his U.S. Pat. No. 4,560,507. The experiments described in that patent application demonstrate that no azetidine formation occurs when using organic solvents such as acetonitrile, methanol, butanol or ethanediol as reaction medium, but cyclization to an azetidine was achieved by the use of an aqueous reaction medium.